narrow vs. wide baffles on speakers

[cwon]

A friend sent me this after I played with baffle sizes on my speakers. Food for thought, so I'm sharing it.


"Aside from WAF, the trend went to narrow baffles because imaging was
the buzz word according to the PHile. Result was crossover correction to
account for step-baffle loss. This just complicated crossovers. Probably,
Harry Olson and others in the 1930's are partly to blame. They deduced
mathematically the optimum shape for imaging, the sphere.

"Of course this really made no sense. What you had as the result was loss of
power or what I call wave launch through the mid-range i.e., dip in actual
response when room loaded. Consider that almost all test are done with a
microphone 1 meter away or at some distance not normally associated with
listening distance.

"Guess that is why horns appeal to certain people. Horns do not suffer this
loss, which also contributes to why horns can sound so real."


I also notice that the speakers in the mastering room Steve used for the CCR SACDs (photo on homepage) are mounted flush with the wall - super wide baffles, I'd say.

[indy mike]

Wanna go for scary? Nosing through old Klipsch papers, they performed a test to see just how critical time alignment of drivers was. A rolling baffle with a tweeter was mounted above a stay-in-place woofer, the test subjects' eyes were covered, the sound generator was cranked up, and when the listener perceived a difference in sound they'd let the tester know. Imagine the surprise when maybe a foot and half or more had been the "I notice a difference" point for folks - just some food for thought...

[Taurus]

My memory is a little fuzzy on this but..........

Back in the 80s, I noticed several companies building very wide enclosures (roughly twice as wide as a "normal" cabinet) including Genesis (http://humanspeakers.com/), Infinity, and Boston Acoustics (http://www.danalexanderaudio.com/forsale.html) (at the bottom of the page; and I don't know this guy!). The theory behind this had something to do with providing a predictable surface for the tweeter and midrange's wavefronts to reflect off of in a controlled manner. This improved stereo imaging.

"Normal" cabinets usually had edges too close to these drivers and those edges themselves--as weird as it may seem--would actually cause reflections that would arrive an instant later after the main (first) wave, and because of the resulting phase differences would cause frequency response variations & possibly smearing of the stereo image. Wave theory can be a brain-melting subject and common sense doesn't always help one figure it out!

This effect is also what prompted other manufacturers to apply some kind of absorbtion material onto the front of the cabinet (i.e. baffle) to simply absorb the unwanted frequencies before they ever had a chance to reflect off of anything in the first place. Acoustic Research used this on some of their models (I think they called it an "acoustic blanket"). Sometimes you'll see just a small amount of it directly around the tweeter--some of JBL's studio monitors (http://www.audioheritage.org/html/profiles/jbl/l100.htm) used this too.

And other manufacturers simply rounded off the edges to help lessen the reflections.

Infinity really got artsy with their low diffraction designs. Their use of gently curving hardwood wings resulted in some beautiful speakers. The Infinity Reference Standard IIA's were the first truly "hi-fi" speakers I listened to (at Pacific Stereo, driven by a huge SAE amplifier. Their 4 ohm rating and dual 10 inchers in a sealed cabinet made this a neccesity). Here is a picture of their slightly upscale brother the RS IIB's which used 3 EMIMs instead of 3 cone midranges, an extra EMIT & the bass controller (scroll down about halfway): Bobby Shred's vintage Infinity page (http://www.bobbyshred.com/infinity.html)

Now back to the 21st century (man it feels weird to say that now!)............

Narrow baffles I think also provide the same benefits as very wide ones (less baffle for reflections to start) but as another poster said I think it's also because of the visual factor: wide speakers just cause too many signifcant-other problems. I thought they looked kinda cool myself!

[T]